Add a SiteEngagementEvictionPolicy.

chrome/browser/engagement/site_engagement_eviction_policy.h

Index: chrome/browser/engagement/site_engagement_eviction_policy.h
diff --git a/chrome/browser/engagement/site_engagement_eviction_policy.h b/chrome/browser/engagement/site_engagement_eviction_policy.h
new file mode 100644
index 0000000000000000000000000000000000000000..effaf8d67464d46bc11d1c115501b2062c551d1a
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+++ b/chrome/browser/engagement/site_engagement_eviction_policy.h
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+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_EVICTION_POLICY_H_
+#define CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_EVICTION_POLICY_H_
+
+#include <map>
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "storage/browser/quota/quota_manager.h"
+#include "url/gurl.h"
+
+namespace content {
+class BrowserContext;
+}
+
+class SiteEngagementScoreProvider;
+
+class SiteEngagementEvictionPolicy
+    : public storage::TemporaryStorageEvictionPolicy {
+ public:
+  explicit SiteEngagementEvictionPolicy(
+      content::BrowserContext* browser_context);
+  virtual ~SiteEngagementEvictionPolicy();
+
+  // Overridden from storage::TemporaryStorageEvictionPolicy:
+  void GetEvictionOrigin(
+      const std::map<GURL, int64>& usage_map,
+      int64 global_quota,
+      const storage::GetEvictionOriginCallback& callback) override;
+
+ private:
+  friend class SiteEngagementEvictionPolicyTest;
+
+  static GURL CalculateEvictionOrigin(
+      SiteEngagementScoreProvider* score_provider,
+      const std::map<GURL, int64>& usage_map,
+      int64 global_quota);
+
+  content::BrowserContext* browser_context_;
+
+  DISALLOW_COPY_AND_ASSIGN(SiteEngagementEvictionPolicy);
+};
+
+#endif  // CHROME_BROWSER_ENGAGEMENT_SITE_ENGAGEMENT_EVICTION_POLICY_H_